Production of stable lubricating oils by sequential hydrocracking and hydrogenation

ABSTRACT

A process is disclosed for producing a lubricating oil having good UV stability from a hydrocarbon feedstock boiling in the range 700* to 1,200*F., which comprises: A. catalytically hydrocracking in a hydrocracking zone said feedstock at a per pass conversion of at least 20 volume percent to materials boiling below the initial boiling point of said feedstock; B. catalytically hydrogenating in a hydrogenating zone at least a substantial portion of the effluent from said hydrocracking zone boiling in the range 550*-1,200*F. at hydrogenation conditions, in the presence of a hydrogenation catalyst comprising 1. A REFRACTORY OXIDE, AND 2. A HYDROGENATING COMPONENT COMPRISING A NOBLE METAL; AND C. recovering as a product of the hydrogenating step a lubricating oil having good UV stability.

United States Patent [191 Stangeland et a1.

[111 3,852,207 1 'Dec.3, 1974 1 PRODUCTION OF STABLE LUBRICATING OILS BYSEQUENTIAL HYDROCRACKING AND HYDROGENATION [75] Inventors: Bruce E.Stangeland, Berkeley;

Clark J. Egan, Piedmont, both of Calif.

[73] Assignee: Chevron Research Company, San

Francisco, Calif.

[22] Filed: Mar. 26, 1973 [21] Appl. No.: 345,142

[52] U.SQ Cl 208/58, 208/18, 208/264 [51] Int. Cl Clog 31/14, Clog 37/10[58] Field of Search 208/58, 18

[56] References Cited UNITED STATES PATENTS 2,960,458 11/1960 Bcuther eta1. 208/19 3,487,005 12/1969 Egan et al 208/59 3,530,061 9/1970 Orkin etal 208/60 3,629,096 12/1971 Divijak 208/89 3,666,657 5/1972 Thompson etal.. 208/58 3,732,156 5/1973 Bennett et all 208/111 PrimaryExaminer-Delbert E. Gantz Assistant ExaminerG. E. Schmitkons Attorney,Agent, or FirmG. F. Magdeburger; R. H. Davies; J. D. Foster 5 7]ABSTRACT A process is disclosed for producing a lubricating oil havinggood UV stability from a hydrocarbon feedstock boiling in the range 700to 1,200F., which comprises:

A. catalytically hydrocracking in a hydrocracking zone said feedstock ata per pass conversion of at least 20 volume percent to materials boilingbelow the initial boiling point of said feedstock;

B. catalytically hydrogenating in a hydrogenating zone at least asubstantial portion of the effluent from said hydrocracking zone boilingin the range 5501,200F. at hydrogenation conditions, in the presence ofa hydrogenation catalyst comprising I 1. a refractory oxide, and 2. ahydrogenating component comprising a noble metal; and g C. recovering asa product of the hydrogenating step a lubricating oil having good UVstability.

10 Claims, No Drawings PRODUCTION OF STABLE LUBRICATING OILS BYSEQUENTIAL HYDROCRACKING AND I-IYDROGENATION BACKGROUND OF THEINVENTION.

I. Field of the Invention The present invention relates to theproduction of stabilized lubricating oils by a combination of catalytichydrocracking and catalytic hydrogenation.

As high quality crude oils for use in preparing lubricating oils becomemore scarce, the economics and desirability of producing satisfactorylube stocks by hydrocracking processes become more attractice. This hasbeen indicated by the increased research activities directed toproducing lube oil stocks by various hydroconversion processes.

One of the major problems with lubricating oils prepared byhydrocracking processes is the instability of the oils in sunlight. Thisinstability to ultraviolet light in the presence of air is evidenced bythe formation of a precipitate after a short period of exposure. Such aprecipitate is undesirable not only because it may prove detrimental tothe lubricating function which the oil is designed to perform, but alsobecause it reduces the aesthetic value of what would otherwise be aclear, premium quality oil. The latter is a true consideration; refinershave learned through experience'that consumers will not buy lubricatingoils which contain visible precipitates, even when those precipitateshave no adverse effect on the performance qualities of the lubricatingoil.

In the past, it has been known that certain types of lubricating oilinstability, such as oxidation instability, couldbe prevented bytreating the oil with any of a number of polar solvents such as phenol,furfural and sulfuric acid (see US. Pat. No. 3,463,724). While thesetreatments tend to remove the instability-causing components, they havethe disadvantage of also removing a considerable portion of thedesirable lubricating oil components. This indiscriminate removel,either by polar extraction or chemical reaction or both, isunsatisfactory since resulting low yields in most instances make theprocess uneconomical.

The present invention is directed to a process whereby the UV stabilityof lubricating oils produced by hydrocracking can be significantlyimproved by catalytic routes avoiding the reduced yields obtained inmany solvent treating processes as well as providing oils with goodoxidation stability.

2. Description of the Prior Art Numerous patents have issued-directed tothe production of lubricating oils. Patents have also issued directed tostabilizing lubricating oils by hydrogenation treatment. For example,US. Pat. No. 3,666,657 teaches a process for improving the qualitystability of hydrocracked oils by hydrogenating the oil subsequent to ahydrocracking treatment over a sulfided mixture of an iron group metaland a metal of Group VI.

US. Pat. No. 3,629,096 teaches preparation .of technical grade whitemineral oil by a series of steps comprising hydrorefining minerallubricating oil distillate in a first zone, taking the hydrogenated oilfrom the first hydrogenation stage and contacting it with hydrogen inthe presence of a hydroisomerization-hydrocracking catalyst followed byhydrogenation over a catalyst comprising a platinum groupmetal on asupport having no substantial cracking effect.

US. Pat. No. 3,530,06l teaches the production of stabilized lube oils byhydrocracking hydrocarbon feed material followed by contacting theproduct from this hydrocracking step with a catalyst havinghydrogenation activity provided by one or more elements from Groups IIB,VIB and VIII at hydrogen pressures in the range from atmospheric up toabout psig.

US. Pat. No. 3,420,768 teaches a method for reducing the pour point of ahydrocarbon middle distillate by hydrocracking the middle distillatefollowed by reduc ing the pour point by contacting the effluent from thehydrocracking zone with hydrogen and a noble metal on alumina.

SUMMARY OF THE INVENTION The subject invention is directed to a processfor producing a lubricating oil of improved sunlight (UV) and goodoxidation stability from a hydrocarbon feedstock boiling in the range offrom about 700 to 1,200F. by a sequential process which comprises:

A. catalytically hydrocracking in a hydrocracking zone said feedstock ata per mass conversion of at least 20 volume percent to materials boilingbelow the initial boiling point of said feedstock;

B. catalytically hydrogenating in a hydrogenating zone .at least asubstantial portion of the effluent from said hydrocracking zone boilingin the range 550-1,200F. at hydrogenation conditions including:

a temperature of from 400 to 700F.,

a pressure of from 1,500 to 5,000 psig,

an LHSV of from 0.2 to 1.5, and

a hydrogen supply rate of from 500 to 20,000

SCF/barrel of said effluent fed to said hydrogenating zone,

in the presence of a hydrogenation catalyst comprisl. a refractoryoxide, and

2. a hydrogenating component comprising a noble metal, and

C. recovering as a product of said hydrogenating a lubricating oilhaving good UV stability.

A preferred catalyst for use in the hydrogenation zone is a noble metalon silica-alumina support wherein the alumina content is at least about40 percent and the composite catalyst has been subjected with the noblemetal in the oxide state to a heat treatment in the range of 1,200 tol,800F. The preferred noble metal is palladium.

DETAILED DESCRIPTION OF THE INVENTION Statement of the Invention Inaccordance with the present invention, there is provided a process forproducing a lubricating oil having good UV stability. 7

The. process comprises the stepsset forth above under the SUMMARY OF THEINVENTION. These steps, which will be described in detail hereinafter,briefly call for:

l. catalytically hydrocracking a hydrocarbon feedstock in ahydrocracking zone at hydrocracking conditions;

2. catalytically hydrogenating at least'a substantial portion of theeffluent from. the hydrocracking zone boiling in the range 550 tol,200F. at hydrogenation conditions with a hydrogenation catalyst; and

3. recovering as a product of the hydrogenation zone lubricating oilhaving good UV stability.

Hydrocarbon Feedstock The hydrocarbon feedstock to the hydrocrackingzone may encompass a wide range of feedstocks boiling in. the range offrom about 700 to about 1,.200F. It may be a heavy straight run gas oil,deasphalted oil, vacuum gas oils, atmospheric residua, or the like.Preferred feedstocks are vacuum gas oils boiling in the range of fromabout 700 to about 1,050F. and solvent deasphalted oils having boilingranges of from about 900 to about l,200F. Reduced topped crude oils aswell as atmospheric residua and the like may also be used. Because ofthe poisoning effect on the catalyst caused by cracking of asphaltenesto coke, it is preferred that the hydrocarbon feedstocks to the hydrocracking zone contain less than about 5 percent by weight ofasphaltenes, preferably less than 1 percent by weight. The hydrocarbonfeedstock has a boiling range extending over at least about 100F. Whilethe sulfur and nitrogen content of the hydrocarbon feedstock to thehydrocracking zone is not critical, excessive quantities of eithersulfur or nitrogen are not desirable. Preferred feedstockscontain lessthan about 3 percent of sulfur and less than about 1 percent of nitrogenby weight.

, Operating Conditions in the Hydrocracking Zone Process conditions inthe hydrocracking zone are those typical of hydrocracking operations. Atemperature of about 500 to 900F., preferably 650 to 800F., is used. Apressure of from about 500 to about 10,000 psig, preferably 500 to 3,000psig, is used with a LHSV of from 0.2 to 5.0, preferably 0.5 to 2.0,more preferably 0.5 to 1.0.The hydrogen supply rate (makeup and recycle)to the'hydrocracking zone is in ther'range of from about 500 to about20,000 standard cubic feet per barrel of hydrocarbon feed, preferablyabout 2,000 to about 10,000 standard cubic feet per barrel.

it should be noted that while hydrocracking is the primary reactionbeing carried out, the feedstocks as noted above generally contain somehetero organic compounds of sulfur, nitrogen, oxygen and even metals insome cases. Therefore, h ydrodesulfurization, hydrodenitrification, etc.may also be occurring.

Hydrocracking Catalyst The catalysts employed in the hydrocracking zoneare comprised of materials having hydrogenationdehydrogenation activity,together with an active cracking component support. These catalysts arewell known in the art as evidenced by the wide range of patent andliterature references. Exemplary cracking component supports includesilica-alumina, silicaalumina-zirconia composites,'acid-treated clays,crysoxides and sulfides of molybdenum and tungsten. Thus,

examples of a hydrocracking catalyst which would be preferred for use inthe hydrocracking process step are the combinations ofnickel-tungsten-silica-alumina, nickel-molybdenum-silica-alumina andcobaltmolybdenum-silica-alumina. Such catalysts may vary in theiractivities for hydrogenation and for cracking and in their ability tosustain high activity during long periods of use depending on theircompositions and methods of preparation. Obviously, the best provencatalysts available are selected, taking into consideration the abovefactors and cost.

A particularly preferred hydrocracking catalyst is a nickelsulfide-tungsten sulfide catalyst on a silicaalumina-titania support.

Conditions in the Hydrogenation Zone The process conditions in thehydrogenation zone include a temperature inthe range of from about 400to 700F., preferably 500 to 600F., a pressure of from about 1,500 to5,000 psig, preferably 2,000 to 3,000 psig, an LHSV in the range of fromabout 0.2 to 1.5, preferably 0.2 to 1.0, more preferably 0.3 to 0.7, anda hydrogen supply rate (makeup and recycle) in the range of from about500 to about 20,000 standard cubic feet per barrel of hydrocarbon feed,preferably from about 2,000 to about 10,000.

Preferred operating conditions are a temperature in the range of fromabout 500 to 600F., a pressure in the range of from about 2,000 to 3,000psig, an LHSV of from about 0.3 to about 0.7, and a hydrogen supply rateof about 2,000 to about 10,000 standard cubic feet per barrel ofhydrocarbon feed.

Particularly preferred conditions are a temperature of about 550F., apressure of about 2,400 psig, an LHSV of about 0.5, and a hydrogensupply rate of about 8,000.

Hydrogenation Catalyst The hydrogenation catalysts contemplated asuseful herein for stabilizing the lube oil product obtained from thehydrocracking zone are those having a Group VIII noble metal componenttogether with a refractory oxide support. Metals contemplated as usefulinclude ruthenium, rhodium and palladium, as well as osmium, iridium andplatinum. Preferred metals are platinum and palladium, more preferablypalladium. The refractory oxide supports may include silica-alumina,silicaalumina-zirconia, etc.

A preferred hydrogenation catalyst is palladium or platinum deposited ona silica-alumina support having an alumina content of from 40 to 95weight percent, preferably 50 to percent. That is, the alumina/silicaweight ratio is 40/60 to /5, preferably 50/50 to 80/20. The palladium orplatinum is present in an amount of from about 0.2 to about 10.0 weightpercent, preferably 0.2 to 1.0 percent of the composite. The catalystwith the palladium or platinum in the oxide form is subjected to a heattreatment in a dry nonreducing gas at a temperature in the range from1,200 to 1,800 F. Palladium is particularly' preferred as thehydrogenation component. The silicaalumina support is preferablyprepared by cogellation of the silica and alumina with the palladium orplatinum impregnated on the dried or undried cogel.

The effluent from the hydrocracking zone which is fed to thehydrogenationzone preferably contains no more than about 50 ppm byweight of nitrogen and no more than about 50 ppm by weight of sulfur.Prefera- A range of lubricating oils is obtained from the subjectprocess. As indicated above, the feedstock to the hydrocracking zoneboils over a range which may extend from about 700 to 1,200F. and mustextend over a range of at least about 100F. The product obtained fromthe hydrogenation zone covers a range of lube stocks boiling over arange of at least about 100F. These may range from light neutrals havingSUS viscosities at 100F. of from about 100 to 200 and boiling in therange of 700 to 900F., through medium neutral lubricating oils havingboiling ranges in the range of from about 850 to l,050F., up to andincluding bright stocks boiling in the range of from about l,000 to1,200F.

It is recognized that lubricating oils are not normally specified on thebasis of boiling range, the primary criteria being viscosity andviscosity index. Generally, however, lubricating oils boil essentiallyentirely above 550F., and more generally above 650F. or even 700F., andas high as about 1,200F.

The term lube oil" or alternatively lubricating oil has been usedherein. It should be recognized that the process of the subjectinvention produces material which might also be referred to as lube oilbase stock. Lubricating oils in use today are generally complexcompositions formulated with a range of additives such as antioxidants,extreme pressure agents, VI improvers, corrosionvinhibitors, detergents,dispersants, and the like.

The term good UV stabilityf means that before a level of flock appearsin the hydrocracked oil which is unsatisfactory (moderate flock of thelevel found in mid-Continent solvent refined 100 neutral oil after about1 1 hours when the oil is exposed to UV light, as described in theexample) will be at least about 6 hours. These UV stability values forthe lube oils of this invention compare favorably with a commercial WestCoast solvent-refined I26 neutral oil having 5.1 hours of stabilitybefore a fine light flock appears and 7.0 hours of stability before amoderate flock appears. The oxidation stability, as measured by the testalso described in the example, will be at least about 6 hours,preferably at least 10 hours.

It should be noted that the hydrocracked stabilized lube oils of thesubject invention may be dewaxed using conventional techniques, ifrequired. Such dewaxing may be carried out by either catalytic means orby solvent extraction processes.

This invention will be better understood by reference to the followingexample, which is offered by way of i1- lustration and not by way oflimitation. This example compares lube oils prepared by a process of thegeneral type described by the prior art and lube oils prepared by theprocess of the subject invention.

EXAMPLE 1 California deasphalted oil having the inspection data shown inTable 1 below was hydrocracked under the conditions shown in Table 1.

TABLE I Feed Inspection Hydrocracking Conditions TABLE l-Continued FeedInspection Hydroc racking Conditions Start to 10% by Volume 686/849F. 30to 50% by Volume 944/101 1F.

, Normally, the conditions are one atmosphere of pure oxygen at 340F.and one reports the hours to absorption of 1000 ml. vof O by 100 g. ofoil. In the Oxidator BN test, 0.8 ml. of catalyst is used per 100 gramsof oil and an additive package is included in the oil. The catalyst is amixture of soluble metal-naphthenates simulating the average metalanalysis of used crankcase oils. The additive package is millimoles ofzinc bis polypropylene phenyl dithio phosphate per grams of oil. Theoxidator BN measures the response of a lubricating oil in a simulatedapplication.

The UV stability of the lube oil is measured by placing the oil samplesin glass bottles 16 mm in diameter, 50 mm high and having a wallthickness of about 1 mm. The caps are loosened and the bottles areplaced in a circular rack surrounding a 450 watt cylindrical HanoviaMercury vapor lamp (Product of Conrad Precision Industries, Inc.)mounted in a vertical position. The distance alonga line perpendicularto the longitudinal axis of' the lamp extending from the longitudinalaxis of the lamp to the longitudinal axis of the bottle is 2 /2 inches.The sample is observed over a period of time. At the first appearance ofa light fine floc (small particles suspended in the oil), the time toformation of the floc is noted. The additional time until a moderatefloc or heavy floc is also noted. In some cases of poor stability a ringof precipitated particles is observed clinging to the walls of thebottle.

A portion of the 700F.+ product described above was hydrogenated over anoble metal hydrogenation catalyst containing 0.4 percent palladium on asilicaalumina (40-60 weight ratio of silica to alumina) support whereinthe catalyst had been heat treated in substantially dry nonreducing gasat a temperature of about 1,400F. Run conditions and inspections of theresulting product are shown in Table 11 below.

TABLE 11 Product Inspection I Hydrogenation Conditions (After Dewaxing)2400 psig A second portion of the 700 F.+ product described above washydrogenated over a prior art catalyst hav- 7 ing the properties setforth in Table III below. The

, properties of the resulting products as well as operating conditionsare also shown in Table Ill.

8 2. a hydrogenating component comprising a noble metal; to produce alubricating oil having good UV stability.

AS can be seen matte"dstreatstmbs jagar 1 the noble metal catalyst inthe hydrogenation step resulted in a product havingsignificantlyimproved UV stabilization and oxidator BN stabilization. Stable oil wasstill being produced with this noble metal catalyst when the 2,400 psigtest run was ended at 850 hours, I It is apparent that many widelydifferent embodiments of the invention may be made without departingfrom the scope and spirit thereof; and, therefore, it is not intended tobe limited except as indicated in the appended claims.

Whatis claimed is: 1. A two-stage process for producing a lubricatingoil having good UV stability from a hydrocarbon feedstock boiling in therange 700 to l,200F., which comprises: V A. catalytically hydrocrackingsaid feedstock in a hydrocracking zone at hydrocracking conditions at aper pass conversion of at least 20 volume percent to materials boilingbelowthe initial boiling point of said feedstock; and

cataiytically 'hydrogenating in a hydrogenating zone at leasta-substantial portion of the effluent from said hydrocracking zoneboiling in the range 550-1,200F. at hydrogenation conditions including':

a tanpmtuiaor tro rn i00 to 700l 'i Y a pressure of from 1,500 to 5,000psig, an LHSV of from 0.2 to 1.5, and a hydrogen supply rate of from 500to 20,000

SCF/barrel of said effluent fed to said hydrogenating zone,

inthe presence of 'Yhy'cTr'ogenatiofi catalyst EUfip'rTs ing l. arefractory oxide, and

atis es essential; martin ale hydrogenation conditions include atemperature of from 500 to 600F., a pressure of from 2,000 to 3,000psig, an LHSV of from 0.2 to 1.0, and a hydrogen supply rate of from2,000 to 10,000 SCF/barrel of said effluent fed to said hydrogenatingzone.

3. The process of claim 1 wherein said hydrocarbon feedstock is selectedfrom the class consisting of heavyrun gas oil, deasphalted oil, vacuumgas oil and atmo- 6. The process of claim 5 wherein said hydrogenation Iconditions include a temperature in the range of 500 to 600F., apressure in the range of from about 2,000 to 3,000 psig, an LHSV of fromabout 0.2 to about 1.0, and a hydrogen supply rate of from about 2,000to 10,000 SCFper barrel of hydrocarbon feed to said hydrogenation zone.

7. The process of claim 6 wherein said hydrogenation catalyst has asilica to alumina weight ratio of 40 to 60 and contains 0.4 weightpercent palladium.

8. The process of claim 7 wherein said lubricating oil has,afterdewaxing, a UV stability of at least 9 hours. 7 9. The process of claim6 wherein said hydrogenation catalyst was subjected to said heattreatment at a temperature in the range of 1,200 to 1,800

10. The process of claim 7 wherein said hydrogenation catalyst wassubjected to said heat treatment at:

about 1 ,400F.

1. A REFRACTORY OXIDE, AND
 1. A TWO-STAGE PROCESS FOR PRODUCING ALUBRICATING OIL HAVING GOOD UV STABILITY FROM A HYDROCARBON FEEDSTOCKBOILING IN THE RANGE 700* TO 1,200*F., WHICH COMPRISES: A. CATALYTICALLYHYDROCRACKING SAID FEEDSTOCK IN A HYDROCRACOING ZONE AT HYDROCRACKINGCONDITIONS AT A PER PASS CONVENTION OF AT LEAST 20 VOLUME PERCENT TOMATERIALS BOILING BELOW THE INITAL BOILING POINT OF SAID FEEDSTOCK; ANDB.CATALYTICALLY HYDROGENATING IN A HYDROGENATING ZONE AT LEAST ASUBSTANTIALLY PORTION OF THE EFFLUENT FROM SAID HYDROCRACKING ZONEBOILING IN THE RANGE 550*-1,200*F. AT HYDROGENATION CONDITIONSINCLUDING: A TEMPERATURE OF FROM 400* TO 700*F., A PRESSURE OF FROM1,500 TO 5,000 PSIG, AN LHSV OF FROM 0.2 TO 1.5, AND A HYDROGEN SUPPLYRATE OF FROM 500 TO 20,000 SCF BARREL OF SAID EFFLUENT FED TO SAIDHYDROGENATING ZONE, IN THE PRESENCE OF A HYDROGENERATION CATALYSTCOMPRISING
 2. The process of claim 1 wherein said hydrogenationconditions include a temperature of from 500* to 600*F., a pressure offrom 2,000 to 3,000 psig, an LHSV of from 0.2 to 1.0, and a hydrogensupply rate of from 2,000 to 10,000 SCF/barrel of said effluent fed tosaid hydrogenating zone.
 2. a hydrogenating component comprising a noblemetal; to produce a lubricating oil having good UV stability.
 2. AHYDROGENATING COMPONENT COMPRISING A NOBLE METAL; TO PRODUCE ALUBRICATING OIL HAVING GOOD UV STABILITY.
 3. The process of claim 1wherein said hydrocarbon feedstock is selected from the class consistingof heavy run gas oil, deasphalted oil, vacuum gas oil and atmosphericresidua.
 4. The process of claim 1 wherein said hydrogenation catalystcomprises palladium on an alumina-silica support.
 5. The process ofclaim 4 wherein said hydrogenation catalyst has an alumina to silicaweight ratio of 40-60 to 95-5 and said noble metal is palladium presentin an amount of from 0.2 to 10 weight percent.
 6. The process of claim 5wherein said hydrogenation conditions include a temperature in the rangeof 500* to 600*F., a pressure in the range of from about 2,000 to 3,000psig, an LHSV of from about 0.2 to about 1.0, and a hydrogen supply rateof from about 2,000 to 10,000 SCF per barrel of hydrocarbon feed to saidhydrogenation zone.
 7. The process of claim 6 wherein said hydrogenationcatalyst has a silica to alumina weight ratio of 40 to 60 and contains0.4 weight percent palladium.
 8. The process of claim 7 wherein saidlubricating oil has, after dewaxing, a UV stability of at least 9 hours.9. The process of claim 6 wherein said hydrogenation catalyst wassubjected to said heat treatment at a temperature in the range of 1,200*to 1,800*F.
 10. The process of claim 7 wherein said hydrogenationcatalyst was subjected to said heat treatment at about 1,400*F.